Alan Stubbs believes his Under-21 side took their foot off the gas after taking an early lead against Arsenal.
Apostolos Vellios' fourth-minute strike was cancelled out by a first-half brace from Thomas Eisfeld, leaving Stubbs to admit the team's concentration had dropped upon going ahead.
It ended 2-1 but there were still positives, with the Gunners fielding some big players, including Jack Wilshere and Bacary Sagna.
Everton themselves had Jan Mucha, Tony Hibbert and Thomas Hitzlsperger in the starting XI.
Stubbs told evertonfc.com: "After starting the game so well, we let them come back into it. Once we'd scored I thought we sat off them a little bit and ran a little deeper rather than carry on as we started with good pressing and forcing them into mistakes."
"It was close towards the end. We conceded two goals that I wasn't too happy about to be honest - it was a bit too easy for them, one down our left, one down our right.”
Despite the setback, Stubbs insists his younger players will have benefitted from testing themselves against the likes of Wilshere, Sagna and Emmanuel Frimpong.
He said: "We're disappointed whenever we get beaten but they had a strong side out against us today - a lot of young players, but international players and ones with quite a bit of Premier League experience.
"It was a great test for our lads. With a bit more quality in the final third, we might have been able to get something from the game.
"Johan Hammar had a great chance at 2-1 and really he should have scored. It would have been interesting then at 2-2 to see which way it would go. Fair play to Arsenal - they got the result in the end."